Thursday, 5 July 2018

A Long Goodbye for Slackware

I first heard of Linux in the winter of 1995. I was writing a device driver for Microsoft's Windows NT intending to knock it into shape for industrial use. And complaining about the poor quality of the Windows code. Like all the time. I think just to shut me up, my friend (and boss) Wiljan Derks told me about this Finnish student who was writing a UNIX operating system all on his own. He called it Linux, just because his name was Linus Torvalds.

Linus Torvalds 1995 Amsterdam

I escaped on home leave back to balmy Malaysia in February 1996, and there in the sleepy backwater of Ipoh was this book on Linux, 'Slackware Unleashed'. At the back was glued a CDROM with Slackware release 1.1. It was an omen: I bought the only copy immediately.

And it has been Slackware for 22 years From the first install using 12 floppy disks (cdrom drives were hard to find then) on a suitcase-sized Zeos 80486DX2 souped up to a dizzying 66MHz 12MB DRAM to a tiny unassuming Raspberry Pi Zero W blazing along at 1GHz and 512MB.

Patrick Volkerding, Slackware's Benevolent Dictator for Life
Incredibly, through all these years, just like Linux, Slackware is run by one person: Patrick Volkerding.

Initially I ran a number of operating systems: Windows NT, Slackware and SuSE. But by 2004 I dropped Windows, which I had used since 1984. When Novell bought SuSE I dropped that too, and it had only been Slackware since then.

Slackware has always been slow to release new versions. The emphasis has always been stability, which is perfect for me: I had always been using a mainline Linux as an embedded device, and Slackware was a lot less work.

True it required a much bigger footprint, but hardware got better all the time and since elevator projects had a development time of two years anyway, all it needed was a leap of faith: start development immediately using a desktop and bet on the embedded hardware being able to run Slackware by the time I needed it.

Happily, in 14 years Slackware and Moore's Law has not let me down. Slackware progressed from an Advantech Industrial PC to the Via EPIA to the Intel-based fanless boxes with aplomb.

Advantech IPC
Quanmax Qbox: Intel-based fanless CPU

But then came the ARM-based CPUs like the Beagleboard and the Raspberry Pi. Now a mainline Linux can fit in the palm of your hand.
Raspberry Pi 3

All this required a fair amount of updates. Despite its manual nature we could cope with Slackware updates, until now: browser vulnerabilities sometimes needed three or more upgrades a year. Browsers like Firefox and Chrome were huge applications and a real pain to upgrade manually, so Debian's siren call beckoned.

When the last two installs of Raspbian went without a hitch, it is time to test my main development laptops on Debian. I started with a spare laptop: an ancient Acer Aspire 5050. Debian 9 'Stretch' installed and ran with great ease. 

Debian 9 'Stretch' on an ancient Acer Aspire 5050

True the speakers did not work and the graphics were slower than my tiny Raspberry Pi Zero W's, but Firefox is up to to the minute, so I think this is the start of Slackware's long goodbye.

On second thought, it is more like au revoir, Slackware.

Monday, 2 July 2018

Give your old audio amplifiers a new lease of life with this RM11.90 bluetooth audio receiver

Chinese no-name Bluetooth Audio Receiver
Over the years we kept upgrading the living room audio systems: first turntable gave way to the cassette tape deck, which then changed to the CD player, then mp3 player. This resulted in a few orphaned amplifiers and speakers, especially if they have odd impedances like 4 or 6 Ohms.

These days we play most of our music from smartphones; why not convert them to bluetooth speakers? I used this RM11.90 sgrobot bluetooth audio receiver.

Note the LED, resistor and capacitor
It came with some loose parts: an LED, 100 Ohm resistor and an electrolytic capacitor. Somehow it reminded me of excess bluetooth audio receiver modules off a PCB mainboard for a bluetooth speaker or somesuch now sold off cheaply. The IC markings C7THN5004 did not come up on an Internet search; they look like custom markings. Never mind, better this than discarding it in the municipal landfill. has a good write-up on it:

I soldered the parts on it; it literally took one minute.

The pinouts are printed on the PCB, but here they are anyway:

3rd pin from top: left speaker, 4th pin: right speaker
I powered it from my trusty D-link USB3 hub, which puts out a whopping 2A at 5V.

To test, I connected it to yet another one of my orphaned PC analog speakers with integrated audio amplifier. I used my Raspberry Pi Zero W with a brand-new version of Raspbian (Debian 'stretch') and omxplayer. It worked without fuss.  It came up as WIN-668 and paired without asking for a PIN.

I had less luck with my Raspberry Pi B+. It had built-in analog and HDMI audio and omxplayer just would not work out of the box. I'm sure that is fixable, but that is another blog post.

As usual, if you can't be bothered with this DIY malarkey, you can buy it ready-made for RM16.90:
RM29: Bluetooth audio receiver. The USB connector is for power only
Once the speakers are bluetooth-enabled, especially combined with the Raspberry Pi Zero W, it becomes and Internet of Things (IoT) device. Now applications like your very own DIY Google Home becomes possible.

Not bad for something one step from the rubbish heap. Happy Trails.